The objectives of this proposal are to investigate fat digestion and absorption in suckling rats. In particular, investigations of the physical state of the lipids in the small intestine and the relationship of physical state to milk triglyceride hydrolysis are planned. In addition, investigations as to the importance of two little studied lipolytic enzymes, viz. lingual lipase and pancreatic bile-salt-stimulated experiments will investigate the pathway for phospholipid metabolism in the suckling rat small intestine. In other experiments, the hypothesis that milk triglycerides can be absorbed from the small intestine without prior hydrolysis will be tested. Other experiments will determine the fatty acid chain length specificity for triglyceride synthesis in the suckling rat mucosal cell. Since fat represents the major source of calories during the suckling period, these experiments will provide much needed data on the mechanism of fat digestion and absorption during this critical time of life. Such data are relevant to the human infant and may be important in the proper design of milk formulas.